Outdoor landscaping wall systems such as retaining wall structures comprised of stacked and interlocked precast concrete building blocks are well known. It is common to vertically stack such blocks in horizontal courses, wherein an upper course is offset with respect to the next lower course, so as to provide a retaining wall having a desired inclination. Usually, such blocks are provided with grooves on their top and bottom faces. In this way, interlock connectors can be interposed between two stacked building blocks and fitted in the grooves.
U.S. Pat. Nos. 4,490,075 and 4,815,897, both issued to Risi et al. on Dec. 25, 1984 and Mar. 28, 1989 respectively, teach an interlock block for a retaining wall system. This block has an axially extending projection upstanding from the top surface and the bottom surface has an axially extending recess of a configuration that is complementary to the projection. The projection is inwardly or eccentrically positioned so that when an upper block is connected to a lower block it is offset, creating an inclined wall structure.
U.S. Pat. No. 5,282,700 issued to Rodrique on Feb. 1, 1994 teaches an interlock block connector comprising an elongated main body to be interposed between two blocks. The elongated main body has offset upper and lower portions so as to offset two stacked blocks.
Canadian Patent Numbers 2,115,462 and 2,114,677, both issued to Correia et al. on Aug. 12, 1995 and Dec. 30, 1997, respectively, disclose blocks for constructing retaining walls having opposed flat top and bottom surfaces with respective grooves formed therein. Connecting elements are disposed within the grooves and interposed between two stacked blocks. The grooves are asymmetrically positioned so as to create an offset between two interconnected blocks.
U.S. Pat. No. 5,248,226 issued to Risi et al. on Sep. 28, 1993 teaches a connector for stackable blocks having offset upper and lower portions; the blocks have asymmetrically positioned grooves on their top and bottom surfaces hence, when blocks are vertically stacked, one course of blocks is offset with respect to the next course. A variety of connectors are provided having different configurations, such as a cylindrical upper body portion so as to allow one block to be pivoted about the connector with respect to a lower block.
A drawback with the prior art is that the same interlock connector cannot be used with blocks having symmetrical grooves to create more than one offsetness. Another disadvantage with the prior art is that connectors that allow an upper block to be pivoted with respect to a lower block are not of a generally rectangular configuration and hence, provide less stability and resistance against transversal displacement.